1. Field of the Invention
The present invention relates to a fuel supply system mounted in an automobile fuel tank and used for supplying fuel under pressure to an injector for emitting a jet of fuel to an automobile engine.
2. Description of the Related Art
FIGS. 5 and 6 show a conventional fuel supply system shown in International Publication No. WO96/23967: FIG. 5 is a side sectional view and FIG. 6 is a plan view.
In these drawings, reference numeral 1 denotes a fuel supply system, which comprises a cover 3, a fuel pump 4, a fuel filter 5, a pressure regulator 6, a fuel level gauge 7, an electric connector 8 and a discharge pipe 9, these being integrally formed and suspended down the open side 2a of a metal or plastic fuel tank 2.
The fuel filter 5 is formed with a holding member 5a made of conductive plastic material and a filter element 5b contained therein, these being liquid-tightly sealed by welding the cover 3 to a boundary portion 10. The holding member 5a holds the fuel pump 4 in its center, the pressure regulator 6 and the fuel level gage 7 in its lower end portion. A gasket 11 for keeping air-tightness is also held between the cover 3 and the fuel tank 2.
In the holding member 5a of the fuel filter 5, an inlet portion 12 as a fuel inlet for the fuel filter 5 is provided on the upper inner peripheral side of the holding member 5a and coupled to the discharge pipe 13 of the fuel pump 4. A pipe 14 (shown by a chain line) forming a first fuel outlet out of the two fuel outlets of the holding member 5a extends upward along the axial direction from the lower end of the holding member 5a. The pipe 14 communicates with the discharge pipe 9 provided to the cover 3 whereby to form a fuel passage for use in supplying filtered fuel. A return pipe 15 forming a second fuel outlet is provided in the lower side portion of the holding member 5a. A strainer 16 is used for filtering off foreign matter such as iron powder in the fuel tank 2 when the fuel in the fuel tank 2 is sucked into the fuel pump 4.
The electric connector 8 is formed integrally with the cover 3 by embedding a plurality of terminal pins 8a and 8b in the insulating plastic material of the cover 3 by direct insert molding. The terminal pins 8a and 8b of the electric connector 8 are connected to one side of a power supply relay (not shown) and a battery (not shown) outside the fuel tank 2. Moreover, the electric connector 8 is also used to supply power to the motor (not shown) of the fuel pump 4 via a lead wire 20 within the fuel tank 2.
Further, an electric signal derived from the fuel level gage 7 indicative of the liquid level is taken out of the fuel tank 2 similarly via a terminal pin (not shown) and a lead wire (not shown).
In the fuel supply system 1 thus arranged, the fuel in the fuel tank 2 is sucked through the strainer 16 when the fuel pump 4 is supplied with power via the electric connector 8 and the lead wire 20 and operated. Then the fuel flows in a passage 17 in the direction of an arrow A after being discharged from the discharge pipe 13 and passes through the filter element 5b before reaching a lower space 18 beneath the filter element 5b.
Further, part of the fuel is returned to the fuel tank 2 again by the pressure regulator 6 for the purpose of adjusting the fuel pressure, whereas the rest of fuel is caused to flow in the pipe 14 in the direction of an arrow B and supplied to the injector of a fuel injection system of an engine (not shown) via the discharge pipe 9.
As static electricity is generated because of intense friction between the fuel and the filter element 5b when the fuel passes therethrough during the process of feeding the fuel, the static electricity has been designed to be dissipated from a relay terminal 19 secured to the inner peripheral portion of the holding member 5a via the lead wire 20 toward the terminal 8b.
However, the prior art fuel supply system above may be used in the electrostatically charged condition because it is not possible to externally confirm the slip-off of the relay terminal 19 secured to the holding member 5a used to dissipate the static electricity or the disconnection of the lead wire 20.
When the fuel pump 4 is operated for hours, moreover, the filter element 5b may be clogged with powder deriving from the wearing of slide parts such as brushes in the fuel pump 4 and a commutator and/or the foreign matter passed through the strainer 16, for example, may be introduced into the fuel pump 4. As a result, the operation of the engine has become unstable because the fuel pump 4 is unable to sufficiently supply the fuel to the injector of the fuel injection system of the engine.